Collapsible structures are known in which a flexible covering is supported by a framework of flexible poles that are interconnected by hubs. For example, a wall of the flexible covering may include pockets at its corners in which outer ends of each of the fabric poles are disposed. The inner ends of the flexible poles are pivotally connected to a hub. The hub allows movement of the flexible poles between collapsed and deployed positions. In the collapsed position, the outer ends of the flexible poles could be adjacent to one another, and the wall of the flexible cover is not held taut. In the deployed position, the flexible poles establish a somewhat planar configuration for the wall of the flexible cover and are held in an over-center condition with respect to the hub by tension that is induced within the poles by the wall of the flexible cover. A structure of this general type is shown in U.S. Pat. No. 3,810,482.